I do a chair test, and then assign parts 1st chair 1st part, 2nd chair 2nd part, etc. it puts my best on all the parts and my weakest on parts with strong players to help them develop. I will also swap parts each piece, so every kid gets the gamut of experience and no one has to muscle through the whole concert on 1st (looking at you, trumpet 1...).

Iíve found it helps found out my players and teaches them to listen to the other parts more.